JP3105968B2 - Paint flow control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paint flow control apparatus, and more particularly to a paint supply apparatus for a painting robot used for painting automobiles, household electric appliances, furniture, etc., which require a high painting quality. The present invention relates to a paint flow control device to be used.

[0002]

2. Description of the Related Art Industrial robots have been widely used in recent years due to advances in electronics technology. In the field of coating, automation is being promoted for the purpose of environmental improvement, labor saving, and further improvement of coating quality.

[0003] In the automation of coating, a high degree of workability of a coating robot relating to actual coating is required, and a high level of flow control performance of a coating material supply device for supplying coating to the coating robot is required.

A paint flow control device disclosed in Japanese Patent Application Laid-Open No. 3-25514 has been proposed in response to such a demand. This paint flow rate control device uses a mass flow meter as a flow meter for comparing and measuring the flow rate of paint, and further improves the accuracy of flow rate measurement by providing a timer corresponding to the response delay time of the flow meter. Further, the control for the delay time is performed based on the stored value of the control signal in the previous coating operation, thereby realizing highly accurate flow rate control.

[0005]

However, in the conventional paint supply apparatus, air bubbles are mixed in the paint tube for supplying the paint, so that the measurement of the flow meter becomes inaccurate and the uniformity of the coating film is deteriorated. There was a case. In addition, water hammer due to paint in the tube and expansion and contraction of the resin tube occur during feedback control during flow control for short-time intermittent command flow, making flow meter measurement inaccurate and mass flow meter Due to the measurement delay, the flow control became unstable, and hunting and overshoot sometimes occurred. For example, in spite of the fact that the flow rate is actually zero, a small amount of paint flows into the flow meter in a short time due to the expansion of the resin tube, so that a flow signal is output and the response of the flow measurement is poor. In addition, since the control based on the change in the number of revolutions of the pump is performed based on the flow rate signal output with a delay with respect to the actual change in the flow rate, in extreme cases, the paint is controlled by reversing the flow control pump. There was a possibility that a phenomenon of pressure feeding in the reverse flow direction might occur.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is possible to avoid a response delay in flow control, detect air bubble mixing in a tube, achieve uniform coating film, and provide a short-term intermittent command flow. It is an object of the present invention to provide a paint flow control device capable of performing a stable flow control with respect to a paint.

[0007]

According to the first aspect of the present invention,
A paint delivery means for delivering the pressurized paint, a paint pipe for supplying the paint delivered by the paint delivery means to the coating gun, and a paint pipe provided in the paint pipe and fed through the paint pipe. A flow rate measuring means for measuring the flow rate of the paint, a feed-forward operation for forming a control signal corresponding to a flow rate value of a preset command flow rate and a flow rate value of the command flow rate and a flow rate measurement value from the flow rate measuring means; A control means for supplying a control signal to the paint delivery means by a feedback operation for forming a control signal based on the difference to control a flow rate of the paint supplied through the paint pipe; And a bubble detection means for outputting a bubble detection signal to the control means when the air bubble mixture is detected. The control means outputs a bubble detection signal from the bubble detection means. The feedforward operation without performing the feedback operation when it is characterized in that it comprises a structure for controlling the paint delivery means.

According to a second aspect of the present invention, the control means includes:
Zero paint means for outputting a zero cut command for controlling the paint delivery means so that the flow rate of the paint in the paint pipeline becomes zero when the flow rate of the command flow rate is equal to or less than a predetermined value. It is characterized by the following.

According to a third aspect of the present invention, the control means includes:
Storage means for storing an error signal that is a difference between the flow rate value of the command flow rate and the flow rate measurement value output from the flow rate measurement means; and a flow rate value of the command flow rate based on the error signal stored in the storage means. And a correction means for outputting a correction signal for correcting

According to a fourth aspect of the present invention, the air bubble detecting means includes two valves provided at a predetermined portion in the paint pipeline and a portion of the paint pipeline separated by the two valves. Bubble mixing determining means for determining that air bubbles are mixed in the paint pipe when a predetermined flow signal is output from the flow measuring means when the paint supplied through the flow measuring means is supplied. And characterized by having:

[0011]

According to the first aspect of the present invention, the control means for controlling the flow rate by the feedback operation and the feedforward operation is provided, so that hunting, overshoot and the like which occur only in the feedback operation are reduced, and the feedforward operation is performed. It is possible to eliminate a steady-state error that occurs only in the case of the above. Further, the feedback operation is not performed when bubbles are mixed in the paint pipe by the control means, so that an erroneous flow signal of the flow rate measuring means caused by the bubbles does not affect the flow rate control.

According to the second aspect of the present invention, the command flow rate equal to or less than the predetermined flow rate value is cut off by the zero cut means.

According to the third aspect of the present invention, the flow rate control signal is corrected by the correction signal from the correction means, so that the flow rate control in consideration of the past actual flow rate is performed.

According to the fourth aspect of the present invention, when air bubbles are mixed in a predetermined portion in the paint pipe, the volume of the air bubbles is compressed by the supply of the pressurized paint, so that a predetermined flow signal is output from the flow rate measuring means. Is output.

[0015]

FIG. 1 is a system diagram of a paint flow control device according to an embodiment of the present invention. The paint flow control device shown in FIG. 1 includes a color change valve 1 for switching the color of the paint or for switching between the paint and the thinner for cleaning and the air for cleaning, a regulator 2a for setting the flow rate and pressure of the fluid, and a mass of Coriolis type. A flow meter 3 (flow rate measuring means) comprising a flow meter for measuring an instantaneous flow rate and an integrated flow rate of the fluid, a gear pump 4a (the paint feeding means) for pumping paint at a pressure corresponding to the flow rate, and opening and closing by supplying an air signal Valve 5
a, 6a and a coating gun 7 for spraying the coating material on the object to be coated are connected by a coating tube 8 (the coating conduit).

The paint flow control device comprises a converter 2b,
The control circuit 9 (the control means) for controlling the regulator 2a, the valves 5a and 6a via the controllers 5b and 6b and the controller 4b, and the memory 1 connected to the control circuit 9
0 (storage means), a residual bubble determination circuit 11 (bubble mixing determination means), and a zero cut circuit 12 (zero cut means).

The valve 6a provided at the forefront of the tube 8 is called a trigger valve, and is provided for the purpose of preventing the rising of the paint at the time of spraying and the cutting of the paint at the stop due to the elasticity of the tube 8 from being deteriorated. Have been. The valve 6a is actually built in the coating gun 7, and is shown adjacent to the coating gun in FIG. 1 for convenience of explanation.

In the paint flow control device having the above-described structure, the paint, thinner or air of each color supplied to the color change valve 1 is changed by the control of the control circuit 9 to which a command signal is supplied according to the setting of a host computer (not shown). It is appropriately selected by the valve 1. Further, the flow rate and pressure of the paint and the like are set by the regulator 2a, and the flow rate is measured by the flow meter 3. Further, fine flow rate control is performed by controlling the rotation speed of the gear pump 4a, and the paint is sent to the coating gun 7 by opening the valves 5a and 6a. In addition, the tube 8 to which the paint, the thinner and the like are transported is generally made of a flexible resin such as Teflon so that the coating gun 7 can easily move in accordance with the coating location.

Control circuit 9 according to a flow signal from flow meter 3
Thus, the regulator 2a or the gear pump 4a is controlled. As the regulator 2a, what is called an air-operated regulator used for controlling the flow rate of paint in general is used. However, the present invention is not limited to this, and an electric control valve may be used.

The converters 2b, 5b and 6b convert an electric signal output from the control circuit 9 into an air signal. For example, a 4 to 20 mA electric signal is converted to 0 to 2 kg / cm
Convert to the air signal of ² . However, the converter 6b may be a simple electromagnetic valve, and the air pressure may be turned on and off by opening and closing the solenoid valve.

FIG. 2 is a perspective view of a painting robot apparatus to which the paint flow control device according to one embodiment of the present invention is applied.
In the figure, a workpiece 21 as a workpiece is a conveyor device 2.
In the coating process transported in the direction of arrow X by 2,
A painting robot 23 is installed near the conveyor device 22. The painting robot 23 is controlled by a controller 38 so that each movable part is controlled by a controller 38, and a predetermined teaching is performed before the work 21 passes the painting work position. Carry out the painting work.

In FIG. 2, a turning drive section 25 is provided on a base 24. A turning base 26 that rotates about an axis A fixed to the base 4 is provided on the turning drive unit 25. A first arm 27 that rotates about an axis B orthogonal to the axis A of the turning base 26 is provided on a bracket 26 a on the turning base 26. Also, the bracket 6a on the turning base 26
Is provided with a first arm drive unit 28.

At the upper end of the first arm 27, the first arm
A second arm 29 that rotates about an axis C parallel to the axis B of the arm 27 is provided rotatably. A second arm drive unit 30 is provided at a connection between the second arm 29 and the first arm 27. Also, the second arm 2
At the rear of 9, a wrist drive unit 31 is provided. Further, a wrist mechanism 32 is provided at the tip of the second arm 29. The wrist mechanism 32 is provided with cases 33 and 34 and a mounting shaft 35. The case 33 rotates about an axis D parallel to the axis C of the first arm 29. The case 34 rotates around an axis E orthogonal to the axis D of the case 33.
The mounting shaft 35 is a mounting portion of the coating gun 7 and the case 34
Are pivoted about an axis F orthogonal to the axis E of FIG.

The coating gun 7 sprays paint by a mechanism as described above while freely moving in accordance with teaching data input in advance, and sprays paint having a predetermined color on the work 21.

FIG. 3 is a block diagram of a command portion of the control circuit 9 of FIG. The command portion in FIG. 3 is entirely constituted by a microcomputer called a sequencer. In the figure, reference numeral 41 denotes a microprocessor, which is instructed by a host computer (not shown) to indicate the type of fluid such as paint and thinner and the flow rate, and outputs a flow rate command signal via a digital-to-analog converter 42 in accordance with the instruction. A zero cut signal, a feedback on / off signal, an integrator on / off signal, and a valve control signal, which will be described later, are output via the ports 43 and 44.

FIG. 4 is a circuit block diagram of the flow velocity control circuit in the control circuit 9. In the figure, a flow velocity command signal is amplified by an amplifier 46 and added by an adder 47 to a feedback signal supplied via a switch 48. Further, the output of the rotational speed detector 50 is subtracted from this signal by a subtractor 49 via a switch 51 and supplied to a servomotor 53 corresponding to the controller 4b of FIG. The servo motor 53 drives the gear pump 4a according to this signal. The output of the servo motor 53 is detected by the rotation speed detector 50 and fed back to the subtractor 49. The operation of the gear pump 4a is accurately controlled by this feedback operation.

Further, a small flow rate equal to or less than a predetermined value is obtained by the zero cut signal supplied from the parallel input / output port 43 of FIG.
In other words, the servo motor 5 responds to the flow velocity command signal corresponding to the flow rate in the zero cut area (for example, 20% of the full scale).
3 is controlled not to operate. The signal amplified by the amplifier 46 is delayed by the delay unit 54 for a time equal to the operation delay time of the flowmeter 3 and supplied to the subtractor 55. Further, the flow rate value supplied from the flow meter 3 is converted into a flow velocity value, and is converted into a flow velocity detection signal of an analog signal by a subtractor 55
Supplied to

Here, the flow velocity detection signal is subtracted from the flow velocity command signal output from the delay unit 54, and a difference between the command flow velocity and the actual flow velocity value, that is, an error signal is generated. This delay device 5
Since the time delay is equal to the operation delay time of the flow meter 3 at 4, the flow rate of the paint is controlled via the gear pump 4a by the flow rate command signal, and the result is detected and fed back by the flow meter 3, particularly, An error due to a time delay caused by an operation delay of the flow meter 3 is removed.

The error signal from the subtractor 55 is supplied to the amplifier 5
6 and to the adder 47 via the switch 48.
Here, the flow velocity command signal and the error signal directly supplied via the amplifier 46 are added, and the flow velocity command signal is corrected by the error signal.

Further, when a feedback on / off signal is output from the parallel input / output port 43 or a bubble detection output is output from the flow meter 3, the switch 48 is opened by the output from the OR circuit 59. The flow command signal is not corrected by the error signal. Therefore, the flow rate detection signal from the flow meter 3 in a state where correct measurement cannot be performed due to air bubbles is not used for feedback control, and the feedback control is prevented from being disturbed by an erroneous flow rate detection signal. The flow meter 3 of the mass flow meter has a gas-liquid discrimination output circuit 3a that detects bubbles by detecting the amplitude of the sensor tube, and outputs the bubble detection output from the gas-liquid discrimination output circuit 3a to a logical OR circuit. It is output to 59.

When a flow rate integration on / off signal is supplied from the parallel input / output port 43, the switch 57 is closed, and the pulse-like flow rate output from the flow meter 3 is output to the integration meter 5.
8 and integrated.

As described above, the flow rate control circuit having the above-described structure eliminates the adverse effects of the operation delay of the flow meter 3 and the inaccurate measurement value of the flow meter due to the inclusion of air bubbles, thereby realizing accurate flow rate control. .

FIG. 5 is a time chart of the operation pattern of the paint flow control device when painting the work 21 shown in FIG. As shown in the figure, when painting a work, a feedback ON / OFF signal is supplied and a flow rate integration ON / OFF signal is supplied. Further, at the time of color change, the paint 1 of the previously used color is supplied, then thinner and air are alternately supplied to wash the paint passage, and then the paint 2 to be used next is supplied. At the time of such color change, neither the feedback ON / OFF signal, the flow rate integration ON / OFF signal nor the zero cut signal is output, and the flow rate control for thinner, air, and the like is not performed.

FIG. 6 shows a modified example in which a feedback loop portion including the amplifiers 46 and 52, the delay unit 54, the subtractor 55, the switch 48, and the adder 47 in FIG. FIG. 7 shows a diagram of the operation time chart of FIG. In the figure, the trigger valve signal TV
Is a signal for opening the valve 6a in FIG.
Further, the mass flow velocity command signal FC corresponds to the flow velocity command signal in FIG.

The microprocessor 61 issues a selection signal to the multiplexer 62 by the function of the timer 61d. The mass flow rate command signal FC and the mass flow rate feedback signal FB supplied to the multiplexer 61 are respectively selected by the multiplexer 62 which has received a selection signal issued from the microprocessor 62 for each sampling time T _S , and both are selected for each sampling time T _S Is supplied to the microprocessor 62. Thus, the signals FC and FB are sampled by the microprocessor 61 at the sampling time T _S.

The mass flow velocity command signal FC is supplied to the feedback loop having the above-described structure slightly after the time τ _V at which the trigger valve signal TV is supplied. When the mass flow rate designation signal FC exceeds the zero cut area τ
After the delay time τ _FB of the flow meter 3 has elapsed from _FF, sampling of the mass flow velocity command signal FC and the mass flow velocity feedback signal FB corresponding to the flow velocity detection signal of FIG. This sampling is continued until the time of falling.

The signals FC and FB sampled by the microprocessor 61 are supplied to an analog / digital converter 61a. Each signal FC converted into a digital value by the analog / digital converter 61a,
FB is the difference between the two within the microprocessor 61,
That is, an error signal is calculated. Further, the microprocessor 61 has a zero cut function corresponding to the zero cut means therein, and when the error signal is a minute value equal to or smaller than a predetermined value, the value is forcibly set to zero. This prevents erroneous control due to a measurement error of the flow meter. That is, for example, the resin tube 8 inflates instantaneously due to the pressure of the fluid, and despite the fact that the flow rate is actually zero, a minute amount of mass flow rate feedback signal FB is supplied from the flow meter 3, whereby the mass flow rate command signal If a difference occurs between the FC and the FC, if the difference is minute, the difference is forcibly set to zero, thereby preventing erroneous correction from being performed.

Further, the error signal is temporarily stored in a memory 61c corresponding to the storage means, and an average of a predetermined time (for example, averaging four sample values) is calculated by a function corresponding to the correction means. . The average value of the error signal is converted into an analog value via the digital / analog converter 61b at each sample time T _S and output as a signal corresponding to the correction signal. Further, this output value is added to the adder 6
At 3, it is added to the mass flow rate command signal FC and output as a corrected mass flow rate command signal. This corrected mass flow rate command signal is used as a flow rate command signal by the servo motor 51.
Supplied to The above configuration corresponds to the correction means, and compares the mass flow rate feedback signal FB with the mass flow velocity command signal FC by delaying the operation delay time of the flow meter 3, and calculates an error signal of the difference between the two. Further, the past error signal is stored in the memory 6.
1c, which are further averaged and added to the mass flow rate command signal as a correction signal. By performing such control, even when a short-term intermittent flow is supplied, sampling is started after the elapse of the delay time τ _FB of the flow meter, so that an accurate comparison between the command signal FC and the feedback signal FB is performed. Becomes possible. Further, since the command signal FC is sequentially corrected by the average value of the error signals calculated by this comparison, highly accurate flow control can be performed.

FIGS. 8A, 8B, and 8C are time charts showing the responsiveness of the control circuit having the configuration shown in the block diagram of FIG. 6, respectively. As described above, in this embodiment, the flow rate is controlled by the gear pump 4a. In this case, the servo motor 5 that drives the gear pump 4a is used.
The response delay time 1 is about 20 msec, whereas the response delay of the flow meter 3 is a relatively large value of about 100 msec.

For this reason, in this embodiment, a feed-forward control method which requires only a response delay time of the servo motor 4a of 20 msec for the response, that is, an open-loop control method is applied, and a steady error is avoided in the control accuracy. It is intended to provide both advantages by applying a feedback control method that can be used.

[0041] (A) in FIG. 8 to avoid applying any feedback, i.e. 4 in the switch S ₁ is showing a response when the open state. This is a case where the control method is applied by the feedforward. In this case, the actual flow velocity FA rises with a delay of 20 msec of the response delay time of the servo motor 4a with respect to the pulse-like command signal FC, and the flow velocity conversion value FD of the output of the flow meter gradually rises with a further delay. Here, in the case of the feedforward control, since there is no feedback of the output result, a steady error EC occurs due to wear of the blades of the gear pump 4a or variation in the viscosity of the fluid.

On the other hand, in the case of only the feedback control shown in FIG. 8B, it is necessary to increase the loop gain of the feedback loop in order to obtain sufficient control accuracy. Since the response delay is large, overshoot and hunting occur as shown in FIG.

On the other hand, by applying the control circuit having the configuration shown in FIG. 6, as shown in FIG. 8C, the rise is fast, that is, the response is good, and the command signal FC is applied without any overshoot. It is possible to perform control with high accuracy for following. This is because the command signal FC is compared with the flow velocity detection signal FD supplied from the flow meter 3, that is, the feedback signal FB after the elapse of the response delay τ _FB by the flow meter 3, and the resulting error signal is compared with the error signal. This is achieved by a configuration in which the signal is amplified by an amplifier and added to a feedforward circuit as a correction signal.

Here, the description has been given of the case where the configuration relating to the feedback loop of the flow rate control circuit is realized by a microcomputer. However, the present invention is not limited to this, and the entire configuration shown in FIGS. Needless to say, it can be realized by a microcomputer including the control of the robot.

The detection of bubbles in the tube 8 is performed by the gas-liquid determination output circuit 3a of the flow meter 3 as described above.
Apart from this, there is a method of detecting by the operation of the valves 5a and 6a and the change of the flow detection output of the flow meter 3. FIG. 9 (A)
1 shows the relationship between the flow meter 3, the valves 5a and 6a, and the tubes 8a and 8b in FIG.

9 (B), 9 (C) and 9 (D) show a state in which the coating operation is completed and only the valve 6a is closed, a state where only the valve 6a is closed, and a state in which the valve 6a is closed. A tube 8a between the flow meter 3 and the valve 5a in each state in which the valve 6a is closed and the valve 5a is opened.
5 shows the change in the pressure inside the tube 8b between the valve 5a and the valve 6a. By operating each of the valves 5a and 6a so as to sequentially realize the above-described states (B) to (D), the detection of residual air bubbles is performed.

FIG. 10 is a time chart of the operation of the valves 5a and 6a and the flow measurement output value of the flow meter 3 which changes according to the operation. That is, only the valve 6a of FIG. 9B is closed, and the paint in the tube 8a is pressurized during the period B. From the state B, the valve 5a of FIG. 9C is first closed, and then the valve 6a is opened. During this time, the paint in the tube 8a is in a non-pressurized state C. Further, (D) is a state in which the valve 6a is closed, then the valve 5a is opened, and the paint in the tube 8a is pressurized again. The state changes to D.

Here, the tube 8a between the two valves 5a and 6a is once set to a non-pressurized state when shifting from the state B to the state C, and is again set to a pressurized state when shifting from the state C to the state D. Therefore, at this time, if the paint in the tube 8a does not contain air bubbles, the paint is liquid or semi-twisted, so that there is almost no change in volume due to pressurization. Thus the flow meter 3 in the flow of FIG. 10 is not flow almost as represented by Q _2, the flow rate is substantially zero.

[0049] On the other hand, if it contains bubbles, since gas varies greatly volume by pressure, minute paint flows volume has decreased by pressure, a relatively large flow rate occurs as indicated by Q ₁ . The bubbles in the tube 8 can be detected by detecting the difference between the flow rates of Q ₁ and Q ₂ .

It should be noted that the above-described bubble detection operation is performed by the valve 5a,
This is performed before the start of painting the next work 21 in order to open and close 6a. If air bubbles are detected here, the flow meter 3
Is inaccurate, so that the paint flow control is performed only by the feedforward operation without performing the feedback operation.

Further, it is needless to say that each circuit configuration in the control circuit 9 is not limited to the configuration shown in the present embodiment, but may be another circuit configuration having substantially the same function.

In this embodiment, the flow rate is controlled by controlling the number of revolutions of the gear pump 4a. However, the present invention is not limited to this configuration, and the flow rate may be controlled by applying a flow regulating valve or the like.

[0053]

As described above, according to the first aspect of the present invention, there are both advantages of good responsiveness of the feedforward operation and high controllability of the feedback operation, and hunting of the flow rate by the feedback control. Because there is no overshoot, even if the coating is performed intermittently, the water hammer of the pipeline and the expansion and contraction of the resin pipeline do not occur, and the feedback operation is performed when bubbles are detected in the pipeline. Since this is not done, errors in the flow rate measurement values caused by air bubbles are removed, and highly accurate flow rate control can be realized.

According to the second aspect of the present invention, since the flow control is prevented from becoming unstable with respect to the command flow rate of the minute flow rate, the minute flow rate generated due to expansion and contraction of the resin pipe line or the like. Accordingly, the flow rate control is not adversely affected and stable flow rate control can be performed.

According to the third aspect of the present invention, the command flow rate is always corrected by the correction means in accordance with the actual flow rate result, so that a stable flow rate control can be performed even for a short-time intermittent command flow rate. Can do it.

According to the fourth aspect of the invention, since air bubbles in the pipeline can be reliably detected with a simple configuration, erroneous control due to air bubbles is prevented, and highly accurate flow rate control is realized. it can.

[Brief description of the drawings]

FIG. 1 is a system diagram of one embodiment of the present invention.

FIG. 2 is a perspective view of a main part of the painting robot according to one embodiment of the present invention.

FIG. 3 is a block diagram of a control circuit of FIG. 1;

FIG. 4 is a circuit block diagram of a flow control circuit in the control circuit of FIG. 1;

FIG. 5 is a diagram showing an operation time chart of one embodiment of the present invention.

FIG. 6 is a circuit block diagram of a flow control circuit of another embodiment of the control circuit of FIG. 1;

FIG. 7 is a diagram showing an operation time chart of FIG. 6;

FIG. 8 is a time chart showing the responsiveness of FIG. 6;

FIG. 9 is a diagram illustrating an operation of detecting a bubble.

FIG. 10 is a diagram of an operation time chart of FIG. 9;

[Explanation of symbols]

 Reference Signs List 3 Flow meter (flow rate measurement means) 4a Gear pump (paint supply means) 5a, 6a Valve (pressurized paint supply means) 8 Tube (paint paint line) 9 Control circuit (control means) 10 Memory (storage means) 11 Remaining bubble determination Circuit (bubble mixing judgment means) 12 Zero cut circuit (Zero cut means)

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Makoto Nishimura 1-3-6 Fujimi, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Tokiko Corporation (56) References JP-A-63-116764 (JP, A) JP-A Sho 58-193758 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B05B 12/02 G01F 13/00 G05B 11/32 G05D 7/06 B05D 1/00-1/36

Claims (4)

(57) [Claims] 1. A paint delivery means for delivering a pressurized paint, a paint pipe for supplying the paint delivered by the paint delivery means to a coating gun, and a paint pipe provided in the paint pipe. Flow rate measuring means for measuring the flow rate of the paint to be fed, a feedforward operation for forming a control signal corresponding to a flow rate value of a preset command flow rate, and a flow rate value of the command flow rate and the flow rate from the flow rate measuring means. A control means for supplying a control signal to the paint delivery means by a feedback operation for forming a control signal based on a difference from the flow rate measurement value to control a flow rate of the paint supplied through the paint pipe; Air bubble detection means for detecting air bubble mixing in the road and outputting a bubble detection signal to the control means when detecting the air bubble mixing, wherein the control means outputs a bubble detection signal from the air bubble detection means. Out Paint flow control device, wherein said by the feed-forward operation without performing a feedback operation to become a structure for controlling the paint delivery means when it is. 2. The control device according to claim 1, wherein the control unit is configured to issue a zero cut command for controlling the paint delivery unit so that the flow rate of the paint in the paint pipeline becomes zero when the flow rate of the command flow rate is equal to or less than a predetermined value. 2. The paint flow control device according to claim 1, further comprising a zero cut means for outputting. 3. The storage device according to claim 2, wherein the control unit stores an error signal that is a difference between a flow rate value of the command flow rate and a flow rate measurement value output from the flow rate measurement unit. 2. The paint flow control device according to claim 1, further comprising: a correction unit that outputs a correction signal for correcting the flow value of the command flow based on the signal. 4. The method according to claim 1, wherein the air bubble detecting means includes two valves provided in a predetermined portion in the paint pipe, and a flow meter in a portion of the paint pipe separated by the two valves. And a bubble mixing determining means for determining that bubbles are mixed in the paint pipe when a predetermined flow rate signal is output from the flow measuring means when supplying the paint which has been sent out. The paint flow control device according to claim 1, wherein: